In rice grains, the Waxy (Wx) gene is responsible for the synthesis of amylose, the most important determinant for eating and cooking quality. The effects of several Wx alleles on amylose content and the taste of cooked rice have been elucidated. However, the relationship between artificial selection and the evolution of various Wx alleles as well as their distribution remain unclear. Here we report the identification of an ancestral allele, Wx lv , which dramatically affects the mouthfeel of rice grains by modulating the size of amylose molecules. We demonstrated that Wx lv originated directly from wild rice, and the three major Wx alleles in cultivated rice (Wx b , Wx a , and Wx in ) differentiated after the substitution of one base pair at the functional sites. These data indicate that the Wx lv allele played an important role in artificial selection and domestication. The findings also shed light on the evolution of various Wx alleles, which have greatly contributed to improving the eating and cooking quality of rice.

In rice (Oryza sativa), amylose content (AC) is the major factor that determines eating and cooking quality (ECQ). The diversity in AC is largely attributed to natural allelic variation at the Waxy (Wx) locus. Here we identified a rare Wx allele, Wxmw, which combines a favorable AC, improved ECQ and grain transparency. Based on a phylogenetic analysis of Wx genomic sequences from 370 rice accessions, we speculated that Wxmw may have derived from recombination between two important natural Wx alleles, Wxin and Wxb. We validated the effects of Wxmw on rice grain quality using both transgenic lines and near‐isogenic lines (NILs). When introgressed into the japonica Nipponbare (NIP) background, Wxmw resulted in a moderate AC that was intermediate between that of NILs carrying the Wxb allele and NILs with the Wxmp allele. Notably, mature grains of NILs fixed for Wxmw had an improved transparent endosperm relative to soft rice. Further, we introduced Wxmw into a high‐yielding japonica cultivar via molecular marker‐assisted selection: the introgressed lines exhibited clear improvements in ECQ and endosperm transparency. Our results suggest that Wxmw is a promising allele to improve grain quality, especially ECQ and grain transparency of high‐yielding japonica cultivars, in rice breeding programs.

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Objective. To investigate differences in genetic risk factors for rheumatoid arthritis (RA) in Han Chinese as compared with Europeans.Methods. A genome-wide association study was conducted in China with 952 patients and 943 controls, and 32 variants were followed up in 2,132 patients and 2,553 controls. A transpopulation meta-analysis with results from a large European RA study was also performed to compare the genetic architecture across the 2 ethnic remote populations.Results. Three non-major histocompatibility complex (non-MHC) loci were identified at the genomewide significance level, the effect sizes of which were larger in anti-citrullinated protein antibody (ACPA)-positive patients than in ACPA-negative patients. These

Background: ALK is the key gene controlling rice gelatinization temperature (GT), which is closely associated with the eating and cooking quality (ECQ) in rice (Oryza sativa L.). To date, at least three ALK alleles are thought to be responsible for the diversity of GT among rice cultivars. The ALK c /SSIIa i allele with high activity of the soluble starch synthase IIa (SSIIa) controls high GT, but the accurate functional difference between ALK a and ALK b alleles, both controlling low GT, is not clearly elucidated. Thus, we generated rice near-isogenic lines (NILs) by introducing different ALK alleles into the japonica cultivar Nipponbare (Nip) to clarify the discrepant effects of the two low-GT ALK alleles. Results: The results showed that the function of two low-GT alleles (ALK a and ALK b) was different, and a much lower GT was observed in NIL(ALK b) rice grains compared with that of Nip(ALK a). Moreover, the starches of NIL(ALK b) grains had a higher degree of branching, higher setback, consistence and higher cool pasting viscosity than those of Nip(ALK a). The lower expression level of ALK b , compared with ALK a , resulted in depleted intermediate chains and increased short chains of amylopectin, thus affected the thermal and pasting properties of NILs' grains. Also, the data revealed both low-GT alleles were mainly found in temperate japonica, but more ALK b was found in other subpopulations such as indica as compared to ALK a. Conclusions: Overall, all the results suggested that the function between two low-GT alleles was different, and the distribution of ALK b was much wider than that of ALK a among the subpopulations of cultivated rice.